linux/drivers/leds/led-class.c
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   1/*
   2 * LED Class Core
   3 *
   4 * Copyright (C) 2005 John Lenz <lenz@cs.wisc.edu>
   5 * Copyright (C) 2005-2007 Richard Purdie <rpurdie@openedhand.com>
   6 *
   7 * This program is free software; you can redistribute it and/or modify
   8 * it under the terms of the GNU General Public License version 2 as
   9 * published by the Free Software Foundation.
  10 */
  11
  12#include <linux/module.h>
  13#include <linux/kernel.h>
  14#include <linux/init.h>
  15#include <linux/list.h>
  16#include <linux/spinlock.h>
  17#include <linux/device.h>
  18#include <linux/sysdev.h>
  19#include <linux/timer.h>
  20#include <linux/err.h>
  21#include <linux/ctype.h>
  22#include <linux/leds.h>
  23#include "leds.h"
  24
  25static struct class *leds_class;
  26
  27static void led_update_brightness(struct led_classdev *led_cdev)
  28{
  29        if (led_cdev->brightness_get)
  30                led_cdev->brightness = led_cdev->brightness_get(led_cdev);
  31}
  32
  33static ssize_t led_brightness_show(struct device *dev, 
  34                struct device_attribute *attr, char *buf)
  35{
  36        struct led_classdev *led_cdev = dev_get_drvdata(dev);
  37
  38        /* no lock needed for this */
  39        led_update_brightness(led_cdev);
  40
  41        return sprintf(buf, "%u\n", led_cdev->brightness);
  42}
  43
  44static ssize_t led_brightness_store(struct device *dev,
  45                struct device_attribute *attr, const char *buf, size_t size)
  46{
  47        struct led_classdev *led_cdev = dev_get_drvdata(dev);
  48        ssize_t ret = -EINVAL;
  49        char *after;
  50        unsigned long state = simple_strtoul(buf, &after, 10);
  51        size_t count = after - buf;
  52
  53        if (isspace(*after))
  54                count++;
  55
  56        if (count == size) {
  57                ret = count;
  58
  59                if (state == LED_OFF)
  60                        led_trigger_remove(led_cdev);
  61                led_set_brightness(led_cdev, state);
  62        }
  63
  64        return ret;
  65}
  66
  67static ssize_t led_max_brightness_show(struct device *dev,
  68                struct device_attribute *attr, char *buf)
  69{
  70        struct led_classdev *led_cdev = dev_get_drvdata(dev);
  71
  72        return sprintf(buf, "%u\n", led_cdev->max_brightness);
  73}
  74
  75static struct device_attribute led_class_attrs[] = {
  76        __ATTR(brightness, 0644, led_brightness_show, led_brightness_store),
  77        __ATTR(max_brightness, 0444, led_max_brightness_show, NULL),
  78#ifdef CONFIG_LEDS_TRIGGERS
  79        __ATTR(trigger, 0644, led_trigger_show, led_trigger_store),
  80#endif
  81        __ATTR_NULL,
  82};
  83
  84static void led_timer_function(unsigned long data)
  85{
  86        struct led_classdev *led_cdev = (void *)data;
  87        unsigned long brightness;
  88        unsigned long delay;
  89
  90        if (!led_cdev->blink_delay_on || !led_cdev->blink_delay_off) {
  91                led_set_brightness(led_cdev, LED_OFF);
  92                return;
  93        }
  94
  95        brightness = led_get_brightness(led_cdev);
  96        if (!brightness) {
  97                /* Time to switch the LED on. */
  98                brightness = led_cdev->blink_brightness;
  99                delay = led_cdev->blink_delay_on;
 100        } else {
 101                /* Store the current brightness value to be able
 102                 * to restore it when the delay_off period is over.
 103                 */
 104                led_cdev->blink_brightness = brightness;
 105                brightness = LED_OFF;
 106                delay = led_cdev->blink_delay_off;
 107        }
 108
 109        led_set_brightness(led_cdev, brightness);
 110
 111        mod_timer(&led_cdev->blink_timer, jiffies + msecs_to_jiffies(delay));
 112}
 113
 114static void led_stop_software_blink(struct led_classdev *led_cdev)
 115{
 116        /* deactivate previous settings */
 117        del_timer_sync(&led_cdev->blink_timer);
 118        led_cdev->blink_delay_on = 0;
 119        led_cdev->blink_delay_off = 0;
 120}
 121
 122static void led_set_software_blink(struct led_classdev *led_cdev,
 123                                   unsigned long delay_on,
 124                                   unsigned long delay_off)
 125{
 126        int current_brightness;
 127
 128        current_brightness = led_get_brightness(led_cdev);
 129        if (current_brightness)
 130                led_cdev->blink_brightness = current_brightness;
 131        if (!led_cdev->blink_brightness)
 132                led_cdev->blink_brightness = led_cdev->max_brightness;
 133
 134        if (delay_on == led_cdev->blink_delay_on &&
 135            delay_off == led_cdev->blink_delay_off)
 136                return;
 137
 138        led_stop_software_blink(led_cdev);
 139
 140        led_cdev->blink_delay_on = delay_on;
 141        led_cdev->blink_delay_off = delay_off;
 142
 143        /* never on - don't blink */
 144        if (!delay_on)
 145                return;
 146
 147        /* never off - just set to brightness */
 148        if (!delay_off) {
 149                led_set_brightness(led_cdev, led_cdev->blink_brightness);
 150                return;
 151        }
 152
 153        mod_timer(&led_cdev->blink_timer, jiffies + 1);
 154}
 155
 156
 157/**
 158 * led_classdev_suspend - suspend an led_classdev.
 159 * @led_cdev: the led_classdev to suspend.
 160 */
 161void led_classdev_suspend(struct led_classdev *led_cdev)
 162{
 163        led_cdev->flags |= LED_SUSPENDED;
 164        led_cdev->brightness_set(led_cdev, 0);
 165}
 166EXPORT_SYMBOL_GPL(led_classdev_suspend);
 167
 168/**
 169 * led_classdev_resume - resume an led_classdev.
 170 * @led_cdev: the led_classdev to resume.
 171 */
 172void led_classdev_resume(struct led_classdev *led_cdev)
 173{
 174        led_cdev->brightness_set(led_cdev, led_cdev->brightness);
 175        led_cdev->flags &= ~LED_SUSPENDED;
 176}
 177EXPORT_SYMBOL_GPL(led_classdev_resume);
 178
 179static int led_suspend(struct device *dev, pm_message_t state)
 180{
 181        struct led_classdev *led_cdev = dev_get_drvdata(dev);
 182
 183        if (led_cdev->flags & LED_CORE_SUSPENDRESUME)
 184                led_classdev_suspend(led_cdev);
 185
 186        return 0;
 187}
 188
 189static int led_resume(struct device *dev)
 190{
 191        struct led_classdev *led_cdev = dev_get_drvdata(dev);
 192
 193        if (led_cdev->flags & LED_CORE_SUSPENDRESUME)
 194                led_classdev_resume(led_cdev);
 195
 196        return 0;
 197}
 198
 199/**
 200 * led_classdev_register - register a new object of led_classdev class.
 201 * @parent: The device to register.
 202 * @led_cdev: the led_classdev structure for this device.
 203 */
 204int led_classdev_register(struct device *parent, struct led_classdev *led_cdev)
 205{
 206        led_cdev->dev = device_create(leds_class, parent, 0, led_cdev,
 207                                      "%s", led_cdev->name);
 208        if (IS_ERR(led_cdev->dev))
 209                return PTR_ERR(led_cdev->dev);
 210
 211#ifdef CONFIG_LEDS_TRIGGERS
 212        init_rwsem(&led_cdev->trigger_lock);
 213#endif
 214        /* add to the list of leds */
 215        down_write(&leds_list_lock);
 216        list_add_tail(&led_cdev->node, &leds_list);
 217        up_write(&leds_list_lock);
 218
 219        if (!led_cdev->max_brightness)
 220                led_cdev->max_brightness = LED_FULL;
 221
 222        led_update_brightness(led_cdev);
 223
 224        init_timer(&led_cdev->blink_timer);
 225        led_cdev->blink_timer.function = led_timer_function;
 226        led_cdev->blink_timer.data = (unsigned long)led_cdev;
 227
 228#ifdef CONFIG_LEDS_TRIGGERS
 229        led_trigger_set_default(led_cdev);
 230#endif
 231
 232        printk(KERN_DEBUG "Registered led device: %s\n",
 233                        led_cdev->name);
 234
 235        return 0;
 236}
 237EXPORT_SYMBOL_GPL(led_classdev_register);
 238
 239/**
 240 * led_classdev_unregister - unregisters a object of led_properties class.
 241 * @led_cdev: the led device to unregister
 242 *
 243 * Unregisters a previously registered via led_classdev_register object.
 244 */
 245void led_classdev_unregister(struct led_classdev *led_cdev)
 246{
 247#ifdef CONFIG_LEDS_TRIGGERS
 248        down_write(&led_cdev->trigger_lock);
 249        if (led_cdev->trigger)
 250                led_trigger_set(led_cdev, NULL);
 251        up_write(&led_cdev->trigger_lock);
 252#endif
 253
 254        /* Stop blinking */
 255        led_brightness_set(led_cdev, LED_OFF);
 256
 257        device_unregister(led_cdev->dev);
 258
 259        down_write(&leds_list_lock);
 260        list_del(&led_cdev->node);
 261        up_write(&leds_list_lock);
 262}
 263EXPORT_SYMBOL_GPL(led_classdev_unregister);
 264
 265void led_blink_set(struct led_classdev *led_cdev,
 266                   unsigned long *delay_on,
 267                   unsigned long *delay_off)
 268{
 269        if (led_cdev->blink_set &&
 270            !led_cdev->blink_set(led_cdev, delay_on, delay_off))
 271                return;
 272
 273        /* blink with 1 Hz as default if nothing specified */
 274        if (!*delay_on && !*delay_off)
 275                *delay_on = *delay_off = 500;
 276
 277        led_set_software_blink(led_cdev, *delay_on, *delay_off);
 278}
 279EXPORT_SYMBOL(led_blink_set);
 280
 281void led_brightness_set(struct led_classdev *led_cdev,
 282                        enum led_brightness brightness)
 283{
 284        led_stop_software_blink(led_cdev);
 285        led_cdev->brightness_set(led_cdev, brightness);
 286}
 287EXPORT_SYMBOL(led_brightness_set);
 288
 289static int __init leds_init(void)
 290{
 291        leds_class = class_create(THIS_MODULE, "leds");
 292        if (IS_ERR(leds_class))
 293                return PTR_ERR(leds_class);
 294        leds_class->suspend = led_suspend;
 295        leds_class->resume = led_resume;
 296        leds_class->dev_attrs = led_class_attrs;
 297        return 0;
 298}
 299
 300static void __exit leds_exit(void)
 301{
 302        class_destroy(leds_class);
 303}
 304
 305subsys_initcall(leds_init);
 306module_exit(leds_exit);
 307
 308MODULE_AUTHOR("John Lenz, Richard Purdie");
 309MODULE_LICENSE("GPL");
 310MODULE_DESCRIPTION("LED Class Interface");
 311